1. Department of Otolaryngology and Head and Neck Surgery, Faculty of Medicine, The University of Tokyo, Tokyo 113-8655, Japan
2. Swallowing Center, The University of Tokyo Hospital, Tokyo 113-8655, Japan
3. Department of Dermatology, Faculty of Medicine, The University of Tokyo, Tokyo 113-8655, Japan
4. Scleroderma Center, The University of Tokyo Hospital, Tokyo 113-8655, Japan